A/C Recharge Issue
07-09-2017, 08:58 AM
#1
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A/C Recharge Issue - 1996 4Runner
Hello All,
I need some help determining a problem that I am experiencing with my '96 4Runner SR5.
So the A/C wasn't blowing the coldest air it could, and I decided to try to recharge it with one of those kits you buy at the auto parts store. The outside temperature was in the 90's and I followed the instructions on the bottle correctly. After recharging to the appropriate PSI indicated, in the "green zone" according to the pressure gauge that came with the kit, I started experiencing problems. The AC compressor pulley now rapidly starts and stops, and does not run long enough to make the air cold. Also, there is a strange "thunking" noise coming from the firewall where the Low and High AC pressure lines go in. I did a bunch or researching and most people say that the rapid cycling is due to low freon levels, but I just recharged it. Also, there were lots of threads and articles about the gauges that come with those things not being accurate and that overcharging the system could cause the same issues. My biggest concern is the thunking sound coming from the firewall, and if I place my hand on the high pressure line, I can feel it the most.... so i think it may be my expansion valve? I tried bleeding off some of the freon from the low pressure line, and that seemed to help a bit (the compressor runs for a few seconds now, before cycling off) and I also noticed that there is no bleed valve for the high pressure line too. So I really don't know what to do. People with other vehicles with this problem mention that the high is too pressurized while the low is not pressured enough, so the solution is to bleed off PSI from the high line. But I cannot find where I can bleed off pressure from my high line. Can anyone help me with suggestions on what I can do to fix this? I'm trying to get a good idea of where the problem is before I remove any parts to attempt to replace or repair. Thanks.
I need some help determining a problem that I am experiencing with my '96 4Runner SR5.
So the A/C wasn't blowing the coldest air it could, and I decided to try to recharge it with one of those kits you buy at the auto parts store. The outside temperature was in the 90's and I followed the instructions on the bottle correctly. After recharging to the appropriate PSI indicated, in the "green zone" according to the pressure gauge that came with the kit, I started experiencing problems. The AC compressor pulley now rapidly starts and stops, and does not run long enough to make the air cold. Also, there is a strange "thunking" noise coming from the firewall where the Low and High AC pressure lines go in. I did a bunch or researching and most people say that the rapid cycling is due to low freon levels, but I just recharged it. Also, there were lots of threads and articles about the gauges that come with those things not being accurate and that overcharging the system could cause the same issues. My biggest concern is the thunking sound coming from the firewall, and if I place my hand on the high pressure line, I can feel it the most.... so i think it may be my expansion valve? I tried bleeding off some of the freon from the low pressure line, and that seemed to help a bit (the compressor runs for a few seconds now, before cycling off) and I also noticed that there is no bleed valve for the high pressure line too. So I really don't know what to do. People with other vehicles with this problem mention that the high is too pressurized while the low is not pressured enough, so the solution is to bleed off PSI from the high line. But I cannot find where I can bleed off pressure from my high line. Can anyone help me with suggestions on what I can do to fix this? I'm trying to get a good idea of where the problem is before I remove any parts to attempt to replace or repair. Thanks.
07-09-2017, 09:26 AM
#2
Registered User
High pressure side and low pressure side are at equal pressures when compressor is not running. There is no such thing as bleeding one, or the other.
Always dangerous to mess with high side fittings while the AC is running. You are in over your head, and you don't have the more sophisticated tools and instruments necessary to diagnose your issue.
Seek professional assistance.
Always dangerous to mess with high side fittings while the AC is running. You are in over your head, and you don't have the more sophisticated tools and instruments necessary to diagnose your issue.
Seek professional assistance.
Last edited by millball; 07-09-2017 at 10:45 AM.
07-10-2017, 07:58 AM
#3
Registered User
Yeah, I think you're better off taking it to an A/C shop at this point.
But it does sound like you overcharged the system. There are two pressure switches on the system. The low-pressure switch shuts the compressor off when the low side gets too low, because the compressor needs refrigerant going through it for oiling, no pressure, no refrigerant, not oil, soon, no seals and a ruined compressor. The high-pressure switch shuts the compressor off when the high side gets too high, to prevent the compressor from blowing something up.
Since you probably overcharged it by adding more refrigerant, the lack of cool was probably due to some other problem. Possibly a failing expansion valve? My wife's 96 had that fail a few years ago, everything in she system was fine, good high and low side pressures, it's just that the expansion valve got sticky and eventually wouldn't let anything through. So after it sat for a night, both sides had good 'resting' pressures, turn the A/C on and the high would go up, the low would go down, until the low side switch shut everything down. And then it would sit there like that for hours, not budging.
Took it to an A/C shop to have the R134 sucked out, then she swapped the expansion valve herself, then back to the A/C shop for a vacuum pull and a recharge.
But it does sound like you overcharged the system. There are two pressure switches on the system. The low-pressure switch shuts the compressor off when the low side gets too low, because the compressor needs refrigerant going through it for oiling, no pressure, no refrigerant, not oil, soon, no seals and a ruined compressor. The high-pressure switch shuts the compressor off when the high side gets too high, to prevent the compressor from blowing something up.
Since you probably overcharged it by adding more refrigerant, the lack of cool was probably due to some other problem. Possibly a failing expansion valve? My wife's 96 had that fail a few years ago, everything in she system was fine, good high and low side pressures, it's just that the expansion valve got sticky and eventually wouldn't let anything through. So after it sat for a night, both sides had good 'resting' pressures, turn the A/C on and the high would go up, the low would go down, until the low side switch shut everything down. And then it would sit there like that for hours, not budging.
Took it to an A/C shop to have the R134 sucked out, then she swapped the expansion valve herself, then back to the A/C shop for a vacuum pull and a recharge.
07-17-2017, 04:15 PM
#4
Contributing Member
After years & years of 'recharging' my a/c at home and wasting money at shops, I replaced ALL components last year and have a properly-functioning system again.
https://www.yotatech.com/forums/f2/c...cement-296576/
Andreas
https://www.yotatech.com/forums/f2/c...cement-296576/
Andreas
07-24-2017, 05:22 PM
#5
I learned
I learned the hard way about the recharge kits. My '99 limited started getting warmer. The kit worked okay one year, hooray I fixed it myself and saved! The next year- same thing, only the compressor died after the fill. It's likely I overcharged the system. I probably only had a couple seals that got old and the compressor would've kept going. So now I've got a new compressor and seals. I will only have a shop do the refill; they have the equipment to do it right. AC systems are complex, repairing can be expensive; both facts of life. Mine is an old car, needing maintenance is hardly surprising. Moral: DIY on AC has financial risk. (We all want to save money!)
07-24-2017, 06:07 PM
#6
Registered User
Those auto store ads and commercials are quite convincing though!
Everytime I walk into one of the stores, I feel like I can fix anything.
Tried to recharge one car, nope. Before I ever attempt to repair the ac system, like Andreas said, ALL components likely need replacing. The diy'er does not have the tools to pinpoint exactly where the failure points are. But it is possible to fix an ac system without taking it to a shop, if you replace all the components that cannot be positively determined a-ok (and evac and fill accordingly).
Everytime I walk into one of the stores, I feel like I can fix anything.
Tried to recharge one car, nope. Before I ever attempt to repair the ac system, like Andreas said, ALL components likely need replacing. The diy'er does not have the tools to pinpoint exactly where the failure points are. But it is possible to fix an ac system without taking it to a shop, if you replace all the components that cannot be positively determined a-ok (and evac and fill accordingly).
